Sketching in 3D with air scaffolding

A team of researchers from KAIST have developed a mid-air 3D sketching tool, combining the strengths of gesture and pen input. They say the technique will ease the way for ideation in three dimensions, leading to efficient product design in terms of time and cost.

For a designer’s drawing to become a product, their 2D drawing must be converted into a 3D shape. However, it is difficult to infer accurate 3D shapes that match the original intention from an inaccurate 2D drawing. On the other hand, loss of depth information occurs when a 3D shape is expressed as a 2D drawing using perspective drawing techniques.

To fill in these ‘missing links’ during the conversion, ‘3D sketching’ techniques have been developed. For example, if a designer draws two symmetric curves from a single point of view or draws the same curves from different points of view, the geometric clues that are left in this process are collected and mathematically interpreted to define the proper 3D curve. As a result, designers can use 3D sketching to directly draw a 3D shape as if using pen and paper.

The biggest limitation with 3D sketching tools is that they cannot articulate the design solely using rough hand motions, therefore they are hard to apply to product designs.

Using hand motions to elaborate designs, Professor Seok-Hyung Bae and his team from the Department of Industrial Design integrated hand motions and pen-based sketching, called Agile 3D Sketching with Air Scaffolding, allocating roles according to their strengths. Designers use their hand motions in the air to create rough 3D shapes which will be used as scaffolds, and then they can add details with pen-based 3D sketching on a tablet.

The team came up with an algorithm to identify descriptive hand motions from transitory hand motions and extract only the intended shapes from unconstrained hand motions, based on air scaffolds from the identified motions.

Through testing, the team found that this technique is easy to learn and use. Most importantly, the users can reduce time, while enhancing the accuracy of defining the proportion and scale of products.

Yongkwan Kim, who led the research project, said: “I believe the system will enhance product quality and work efficiency because designers can express their 3D ideas quickly yet accurately without using complex 3D CAD modelling software.”

The KAIST team says that this tool could find application in fields including the automotive industry, home appliances, animations, the movie making industry, and robotics. It can also be used in smart production technology, such as 3D printing, to make manufacturing process faster and more flexible.